The invention relates to a battery with a battery housing and a cooling apparatus for temperature control of the battery, wherein the battery has a plurality of individual cells which are connected in parallel and/or in series with one another.
A battery for use in motor vehicles, in particular in motor vehicles with a hybrid drive or fuel cell vehicles usually has a cell block of a plurality of individual cells electrically connected in series and/or in parallel (also called individual cells), for example, lithium ion cells.
The individual cells have to be cooled in order to discharge the resulting lost heat. For this, a cooling apparatus is used, which is thermally connected to the individual cells.
With a so-called head cooling of the individual cells, the cooling apparatus is arranged at a pole side of the individual cells, where electrical pole contacts of the individual cells are present, which are connected to each other in pairs in an electrically conductive manner using cell connectors.
These batteries are amongst others disclosed in U.S. Pat. No. 6,512,347 B1, DE 100 03 740 C1, DE 602 13 474 T2 and US 2005/0174092 A1.
U.S. Pat. No. 6,512,347 B1 discloses a battery whose cooling apparatus is formed as a cooling tube that can carry a coolant, which tube is connected to the individual cells in a heat-conducting manner via heat-conducting plates arranged between these.
With the battery disclosed in DE 100 03 740 C1, the cooling apparatus is formed as a heat-conducting plate formed on a pole side of the individual cells, which plate is in thermal contact with cell connectors of pole contacts of the individual cells for cooling the individual cells.
With the battery disclosed in DE 602 13 474 T2, the cooling apparatus is formed as a cooling bellows of a deformable heat-conducting material. The cooling bellows is placed around the individual cells in several folds and can be flown through by a heat transfer medium, via which heat can be discharged from the individual cells.
US 2005/0174092 A1 discloses a battery whose cooling apparatus comprises a number of cooling channels. Thereby, for cooling the individual cells, pole contacts of the individual cells and cell connectors electrically connecting them are arranged in the cooling channels and can be cooled convectively using a gas flowing through the cooling channels. The cell connectors preferably have cooling blades extending into the cooling channels in order to enlarge their coolable surface. The cell connector simultaneously serve for fixing the individual cells, in that they are formed as washer elements for screw nuts for the attachment of the pole contacts to walls of the cooling channels.
The present invention provides a battery with improved cooling of the individual cells.
In accordance with exemplary embodiments of the present invention, the battery with a battery housing comprises a plurality of individual cells connected in parallel and/or in series according to the invention, which are attached in a prestressed manner to a cooling apparatus using the cell connectors.
With known batteries with head cooling, the individual cells are usually respectively connected to the cooling apparatus via forces acting upon pole contacts. In contrast, exemplary embodiments of the present invention provide that the individual cells can be attached to the cooling apparatus via a connection that can be prestressed of the individual cells arranged on or in pole contacts of the individual cells in a form-fit and force-fit manner and thus to cell connectors supported thereon. The individual cells are in particular pressed to the cooling apparatus via the prestressable cell connectors to the cooling apparatus, e.g., to an underside of the cooling apparatus. The pulling force to be applied for this is thereby introduced into the individual cells via the cell connectors, so that the pole contacts are relieved mechanically. Using the direct pressing of the individual cells to the cooling apparatus, the cooling of the individual cells and the stability of the cell compound of the individual cells are improved. A durable pre-stressing is additionally effected in the pressing compound of the cooling apparatus and the individual cells over the lifetime of the battery.
In one aspect of the present invention, the cell connectors are formed elastically, in particular resiliently, for a prestressable connection of individual cells and cooling apparatus. Such an arrangement of the prestressable connection has the advantage that the pre-stressing can be adjusted individually for each individual cell by corresponding tightening of the cell connectors e.g., using a screw. Differences of the dimensions of the individual cells caused by manufacture can thereby be compensated for in a particular advantageous manner.
In one aspect of the present invention, the cell connectors have an omega-shaped or loop-shaped longitudinal section. Thereby, the height of the pre-stressing is determined by the distance of the omega legs to the o-shaped or the circular omega element and the height of the hollow space of the o-shaped or the circular omega element. The cell connectors are, for example, arranged in such a manner on the pole contacts that that they depict an omega standing on its head in the longitudinal section of the battery, whose omega legs are attached to the pole contacts of adjacent individual cells and whose circular omega element abuts the face side of the individual cells in a form-fit manner and in a force-fit manner in the assembled state.
The height of the cell connectors is furthermore conveniently larger than the height of the pole contacts of the respective individual cell projecting from the cooling apparatus. During the assembly of the cell connectors to the pole contacts of the individual cells, the cell connectors are prestressed in such a manner that they press the cooling apparatus against the compound of the individual cells in an advantageous manner and thereby produce an improved heat-conducting contact between the cooling apparatus and the cell compound.
Using the contact of the cell connectors to the cooling apparatus, a part of the lost heat generated in the individual cells is additionally transferred to this cooling apparatus via the pole contacts of the individual cells and via the cell connectors arranged on these, which abut the cooling apparatus.
An alternative aspect of the present invention provides that respectively one cell connector is provided with respectively one spring element. In other words, the cell connector has an additional spring element, which is arranged at the cell connector and which is aligned in the direction of the face sides of the individual cells.
For a simple and fast assembly, the respective, in particular s-shaped spring element can be arranged at and attached to the respective cell connector in a form-fit and force-fit manner, in particular a locking manner.
For the electrical insulation with regard to the cooling apparatus, the respective spring element is formed at least of electrically insulating material, e.g., plastics. The respective spring element is furthermore at least temperature-resistant.
The cooling apparatus is preferably a heat-conducting plate which is heat-conducting contact with the individual cells. This enables a simple and installation space-saving construction of the battery.
Using the elastic formation of the cell connectors, they press the heat-conducting plate against the individual cells in a simple manner.
In a further aspect of the present invention, the cell connectors are in heat-conducting contact with the cooling apparatus formed as heat-conducting plate. In order to further improve the heat conduction and to electrically insulate the cooling apparatus against the cell connectors, an electrically insulating heat-conducting film is present on the cooling apparatus, in particular on the upper side in the direction of the cell connectors, in an advantageous arrangement of the invention.
The cooling apparatus, in particular the heat-conducting plate, conveniently has bores and/or incisions in the region of the pole contacts of the individual cells for passing the pole contacts through. The heat-conducting film conveniently also has recesses for passing the pole contacts through.
Additionally, a heat-conducting and electrically insulating molded body can be arranged between the heat-conducting plate and the individual cells. This serves in particular for the electrical insulation of the pole contacts of an individual cell.
For an optimum heat discharge, the heat-conducting plate can have a channel structure for a coolant flowing through this channel structure. The channel structure is, for example, connected to an air conditioning or cooling cycle of the vehicle, wherein, for example, cooling air or a cooling means of the air conditioning system flows through the channel structure of the heat-conducting plate, so that the lost heat of the individual cells transferred to the heat-conducting plate via the coolant can be discharged from the battery.
Furthermore, the respective individual cell preferably has a honeycomb casing, which also enables an optimized cooling in that the honeycomb casing is preferably formed of an electrically insulating material and which conducts heat in a particularly good manner.
The battery is preferably a vehicle battery, in particular a battery for a vehicle with hybrid drive or a fuel cell vehicle.
Parts corresponding to each other are provided with the same reference numerals in all figures.